PHP 5.3 == PHP 6?

Clicked Send too fast. For the suggestion box, let me
instead suggest that for string $s and float $f:
$s == $f (a string being compared to a float) be the same as
(string)(float)$s === (string)$f instead of
(float)$s === $f (as it is today if my understanding is correct)

Since the current behavior is effectively undefined in any
case in which the two interpretations would give different
results, I'd guess that change could probably be made without
breaking BC. The only problem would be if someone relied
on the change and their code was run on an old version of
php.

I'll go back to my corner now. Thanks for listening...

• Todd

I'd take that as proof of a design flaw in having php
doing string to float comparison by casting the string to
float instead of the float to a string, but you've got
me - the documentation does say the string will be converted
to a float and not vice-versa. If it wouldn't be a bad BC
break, I think there'd be a lower WTF by doing the cast
the other way. "==" means are they the same and "==="
means are they the SAME. With "==", '1.8' should match
any float that would be displayed as 1.8. (Of course,
with "===" they aren't even the same type, so you're
false from the start.) I say "should" from an anti-WTF
perspective. Again, I must bow to the spec and you have
me there.

Thanks for saving me the hours of discovering all this
via debugging. Please consider the switching of casts
for string==float for the suggestion box.

• Todd

There is no bug here. Please read:

http://docs.sun.com/source/806-3568/ncg_goldberg.html

-Rasmus

Todd Ruth wrote:

I'm thinking there must be a bug in the heart of php
causing this. I'll debug it, but I haven't looked at
php source code in a few years and would like a tip as
to which files are involved in evaluating "==". Here
is a fragment from my code and the output:

...
print "<pre>\n";
var_dump($max);
var_dump($nms);
var_dump($nms == $max);
$max = (float)$max;
$nms = (string)$nms;
var_dump($max);
var_dump($nms);
var_dump($nms == $max);
$max = (string)$max;
$nms = (float)$nms;
var_dump($max);
var_dump($nms);
var_dump($nms == $max);
print "</pre>\n";
...

string(3) "1.8"
float(1.8)
bool(false)
float(1.8)
string(3) "1.8"
bool(true)
string(3) "1.8"
float(1.8)
bool(true)

I found this using php 5.2.3. I just upgraded to php 5.2.5
and am receiving the exact same result. Obviously, I can't
reproduce it with a simple var_dump("1.8"==1.8). :(
I guess something is getting corrupted, and I will add debug
output until I find out what (or Murphy removes the problem
by adding debug output; then I'm not sure what I'll do).

Thanks for any tips on which files I should look at it.